In vivo activity of cefquinome against Riemerella anatipestifer using the pericarditis model in the duck.

Cefquinome is a fourth-generation cephalosporin with broad-spectrum antibacterial activity, including activity against enteric gram-negative bacilli such as Riemerella anatipestifer. The pericarditis model was used to examine the pharmacodynamic characteristics of cefquinome against R. anatipestifer. Serum levels of cefquinome following the administration of different doses were determined by LC-MS/MS. Ducks with ca. 10(6) CFU/mL at the initiation of therapy were treated with cefquinome at doses that ranged from 0.0156 to 2 mg/kg of body weight/day (in 3, 6, 12, or 24 divided doses) for 24 h. The percentage of a 24-h dosing interval that the unbound serum cefquinome concentrations exceeded the MIC (fT > MIC) were the pharmacokinetic (PK)-pharmacodynamic (PD) parameter that best correlated with efficacy (R(2) 86.3% for R. anatipestifer, compared with 58.9% for the area under the concentration-time curve/MIC and 10.6% for peak/MIC). A sigmoid Emax model was used to estimate the magnitudes of the %fT > MIC associated with net bacterial stasis, a 1-log10 CFU reduction from baseline, and a 2-log10 CFU reduction from baseline; the corresponding values were (22.5 ± 1.3) %, (35.2 ± 4.5) %, and (42.4 ± 2.7) %. These data showed that treatment with cefquinome results in marked antibacterial effects in vivo against R. anatipestifer and that the host's immunity may also play a key role in the anti-infective therapy process.

Antibacterial, anti-inflammatory, and antioxidant effects of Yinzhihuang injection.

The Yinzhihuang injection, a traditional Chinese medicine, has been the recent target of increasing interest due to its anti-inflammatory properties. The molecular basis by which Yinzhihuang injection could cure Riemerella anatipestifer (RA) serositis in ducks is unclear. This study evaluated the antibacterial, anti-inflammatory and antioxidant effects of Yinzhihuang injection, using disease models of RA-induced infectious serositis in ducks and heptane-induced inflammation in mice and rats. The duck mortality rate was reduced from 60% to 20% and both the inflammatory response and histological damage were ameliorated by treatment with Yinzhihuang injection (0.02 g/kg). Further studies indicated that superoxide dismutase (SOD), nitric oxide synthase (NOS), and inducible nitric oxide synthase (iNOS) were elevated while malondialdehyde (MDA), nitric oxide (NO) and RA growth were inhibited when the ducks were treated by Yinzhihuang injection. In addition, Yinzhihuang injection (0.04 g/ml) effectively inhibited xylene-induced auricle swelling in mice, (demonstrating an inhibition rate of 35.21%), egg albumen-induced paw metatarsus swelling in rats, (demonstrating an inhibition rate of 22.30%), and agar-induced formation of granulation tissue. These results suggest that Yinzhihuang injection ameliorates RA-induced infectious serositis in ducks by modulation of inflammatory mediators and antioxidation.